An esophagobronchial fistula developed in a patient who had well-differentiated squamous carcinoma of the lung that was treated with chemotherapy. Because the esophagobronchial fistula could not be surgically repaired, it was isolated with a mechanical stitch above and below it. Forty-eight hours after initiation of enteral nutrition, a perfusion lung scan was performed because of clinical suspicion of pulmonary embolism. Because the scan showed reduced pulmonary radioactivity and accumulation of activity in the kidneys and spine, an arteriovenous shunt was suspected. However, subsequent digital subtraction angiography ruled out this possibility and a recurrence of the esophagobronchial fistula was confirmed with an esophagogram. The unusual extrapulmonary activity could be related to a reversible capillary shunt in the pulmonary vasculature, secondary to acute respiratory distress syndrome.